1. Field of Invention
The present invention relates to roll position alignment that is carried out after rolls are assembled in a bar steel rolling mill. In particular, the present invention relates to a method of adjusting a roll position using a roll caliber and a guidance apparatus for adjusting the roll position.
2. Description of Related Art
In general, the position of a roll assembled in the housing of a bar steel rolling mill is directly visually adjusted by a worker using a gauge or the like.
There is also a method of using an optical gauge. According to this method, the overall image of a roll caliber is enlarged to several tens of times of its actual size and projected onto a screen. Then, a worker visually adjusts a roll position so that the reference profile of the roll caliber displayed on a projecting surface corresponds with the projected image. The roll caliber is a curved position for connecting the points at which a roll is in contact with a material to be rolled and determined by the roll position, the roll surface shape, and the like, in a rolling mill.
In the visual roll position adjusting method, however, the amount of adjustment cannot be quantitatively obtained even if an optical gauge is used. Accordingly, the roll adjustment does not have good accuracy and greatly depends on a worker's skill. The roll position adjusting job is also called a centering job. Moreover, because the adjusting job alone may require a long amount of time depending upon the degree of skill of the worker, there is also a problem that working efficiency is poor.
To address the above problems, Japanese Unexamined Patent Publication Nos. 6-167313 and 8-5343 propose a method of measuring the caliber profile of a roll caliber using image processing and determining the center and the radius of an affine circle corresponding to the thus obtained caliber profile. With this method, it is possible to automatically measure a roll position and to adjust the roll position based on a determined affine circle.
In the method disclosed in Japanese Unexamined Patent Publication No. 6-167313, however, sufficient accuracy cannot be obtained because the roll position is adjusted only by the profile of an actual caliber.
Further, in the methods disclosed in both of the above-mentioned publications, an overall caliber profile must be expressed with an affine circle. For this purpose, measurement must be carried out at many points, whereby control is made complicated.
Moreover, the methods disclosed in both of the above-mentioned publications mainly make use of the profile of the arc portion of a roll caliber in the vicinity of the center of the role caliber in an axial direction. The roll caliber is more worn at its center in the axial direction in rolling. Consequently, there is a possibility that an error is included in an amount corresponding to the amount of wear with respect to the coordinates of the determined affine circle. Thus, there is a possibility that positional accuracy is deteriorated by the amount of error due to the wear.